1. Field of the Invention
The present invention relates to a liquid ejection head and a manufacturing method thereof, and particularly relates to a technique for connecting electrical wires in a high-density liquid ejection head.
2. Description of the Related Art
A known example of an image forming apparatus is an inkjet printer (inkjet recording apparatus) that has an inkjet head (liquid ejection head) with multiple nozzles (ejection ports) arrayed, wherein an image is recorded on a recorded medium by ejecting ink from the nozzles onto the recorded medium while moving the inkjet head and the recorded medium relative to each other.
Such an inkjet printer is designed so that ink is supplied from an ink tank to pressure chambers via an ink supply channel, and a piezoelectric element is driven by sending electric signals corresponding to image data to the piezoelectric element, whereby a diaphragm constituting part of the pressure chambers is deformed, the capacity of the pressure chambers is reduced, and the ink in the pressure chambers is ejected from the nozzles as droplets.
In such an inkjet printer, one image is formed on the recorded medium by combining dots formed by the ink ejected from the nozzles. Recently there has been a demand for forming high quality images to ensure photographic print quality in inkjet printers. One technique under consideration is to achieve high quality by reducing the nozzle size to shrink the size of the ink droplets ejected from the nozzles, and arraying the nozzles in a highly dense arrangement to increase the number of pixels per unit area.
Also, in order to densely array the nozzles, a structure for the electrical wires for driving the nozzles and a method for connecting the electrodes must be designed. Various proposals have been made concerning this matter.
In one known example, high density and low cost are achieved by disposing the nozzles on the side of the piezoelectric element, using a configuration in which an aluminum plug runs through the layered layers, and a head is formed by silicon photoetching (for example, see Japanese Patent Application Publication No. 2000-289201).
Also, in another known example, an inkjet head is provided with excellent refilling capabilities, ink mixing capabilities, and filterability. In this head, sintered stainless steel or another such porous material with multiple small internally connected holes is used as the ink supply plate to enable ink to pass through this portion (for example, see Japanese Patent Application Publication No. 2003-512211).
Also, in another known example, the structure is simplified by connecting driving wires to a mounting unit provided in the area on the side opposite the piezoelectric element (for example, see Japanese Patent Application Publication No. 2003-136721).
However, the example disclosed in Japanese Patent Application Publication No. 2000-289201 has drawbacks in that although a configuration is used in which an aluminum plug passes through the layered layers, silicon photoetching makes it difficult to form deep electrodes and to increase the size of the head.
The example disclosed in Japanese Patent Application Publication No. 2003-512211 has drawbacks in that although a configuration is used in which bumps are formed on both sides of an insulating plate and pressure is applied to the piezoelectric element with an elastic pad to bring out the electrodes, it is difficult to achieve high density and the connection tends to become unstable.
Furthermore, the example disclosed in Japanese Patent Application Publication No. 2003-136721 has drawbacks in that because the wires are connected with the disclosed wiring pattern and wire bonding and the electrodes are brought out in a thin film, it is difficult to form thin and deep wires.